A system of the kind referred to above is disclosed in United States patent application Ser. No. 165,276, filed Feb. 26, 1988. Here, an electronic control arrangement in a motor vehicle is described which is equipped with an arrangement for monitoring measuring units which detect operating parameters of the engine and/or of the motor vehicle. These measuring units are checked with respect to their function by evaluating the signal variables supplied thereby. Fault conditions of the particular measuring unit are detected by comparing the signal variables supplied by the measuring units with pregiven limit values. A check of the signal variable with respect to its limit values pregiven by the supply voltage takes place. The check is explained with respect to an electronic accelerator pedal taken as an example.
A procedure of the kind described above has the disadvantage that the following cannot be detected: shunt faults of the signal line of the measuring unit to the poles of the supply voltages; interruptions with stray resistance to the poles of the supply voltages; and, nonlinearities of the measuring unit. Accordingly, operational reliability of a system equipped with such a measuring unit cannot be ensured.